Greater demands have been Imposed by present-day management practices on the modern dam with gilts being bred at younger ages and lower levels of back fat. This has raised questions over whether current rearing feeding practices and low pregnancy feeding regimes may have adverse Influences on lifetime reproductive performance. The objectives of this experiment were to compare the reproductive performance of sows given different feeding regimes during rearing and pregnancy. Data previously reported from the experiment have shown that the weight and back fat depth of the gilt and sow can be manipulated by feeding regime over the first four parities (Simmins et al. 1989, 1991). Sows reared on the lower feed levels were more prolific 1n their first two Utters, but also had longer, farrowing Intervals (Edwards et al. 1989). These sows remained more prolific by weaning of the fourth Utter (Simmins et al. 1991). Performance over eight litters is described below.